The invention relates to tufting brushes.
Toothbrushes generally include a body having a handle portion, a head portion, and bristles extending from the head portion. The bristles can be arranged in the form of a number of tufts.
Toothbrushes are manufactured by injecting liquid plastic into a mold cavity that defines a toothbrush body. Tufts of bristles are then attached to the head portion of the toothbrush body in a process generally known as tufting. Tufting of toothbrushes can be done by stapling, hot tufting, welding or molding tufts of bristles into the toothbrush body.
The invention relates to a composite mold in which tufts of bristles can be inserted and maintained in a predetermined position while being subjected to an injection molding operation to form a brush. The composite mold includes a mold cavity defining a portion of an oral brush head.
In one aspect, the invention features a composite brush mold that includes a) a first component that includes a pattern of holes extending from a first surface of the first component to a second surface of the first component, the holes being configured to receive tufts that include at least one bristle, and b) a second component that includes a pattern of fingers that correspond to the pattern of holes, the fingers extending into the holes to form end walls.
In some embodiments, the mold further includes a bar that includes an opening extending therethrough, the first component and the second component being positioned in the opening of the bar. In one embodiment, the bar includes a plurality of openings extending therethrough. In other embodiments, the mold further includes a plurality of the first components and a plurality of the second components, in which the first components and the second components are positioned in the openings of the bar. In one embodiment, the opening in the bar extends through the bar in a first direction, and the bar further includes a ledge extending into the opening in a second direction, the second direction being substantially perpendicular to the first direction.
In other embodiments, the first component is plastic. In one embodiment, the first component is plastic and the second component is plastic.
In another embodiment, the bar further includes guide pins positioned to align the first component in the opening of the bar.
In some embodiments, the first component further includes a cavity located at the first surface of the first component such that the holes extend from the cavity, and the cavity defines a portion of an oral brush from which tufts of bristles extend.
In one embodiment, the second component further includes a base, a first finger extending from the base at a first angle to the base, and a second finger extending from the base at a second angle to the base, the second angle being different from the first angle. In other embodiments, the second component further includes a base secured to the first component and the fingers extend from the base. In another embodiment, the mold further includes a cover positioned to maintain the fingers in position within the first component.
In other embodiments, at least one of the holes, when taken in cross-section, defines a shape selected from the group consisting of a circle, triangle, square, rectangle, rhombus, ellipse, star, oval, and crescent.
In another embodiment, the pattern of holes includes a first plurality of holes and a second plurality of holes.
In one embodiment, the second component includes a first plurality of fingers dimensioned to be inserted into the first plurality of holes, and a second plurality of fingers dimensioned to be inserted into the second plurality of holes. In some embodiments, the first plurality of holes extend at a first angle to the first surface, and the second plurality of holes extend at a second angle to the first surface, the second angle being different from the first angle. In some embodiments, the second component includes a base, a first plurality of fingers extending from the base at an angle corresponding to the angle of the first plurality of holes, and a second plurality of fingers extending from the base at an angle corresponding to the angle of the second plurality of holes. In one embodiment, the second component further includes a first subpart that includes a base and a first plurality of fingers corresponding to the first plurality of holes, and a second subpart that includes a base and a second plurality of fingers corresponding to the second plurality of holes.
In other embodiments, the first plurality of holes have a first cross-section, and the second plurality of holes have a second cross-section, the first cross-section being different from the second cross-section.
In one embodiment, the second component further includes a first subpart that includes a base and a first plurality of the fingers corresponding to the first plurality of holes, and a second component that includes a base and a second plurality of the fingers corresponding to the second plurality of holes. The holes of the first plurality of holes can be circular in cross-section, elliptical in cross-section, circular in cross-section, or a combination thereof. The holes of the first plurality of holes can be circular in cross-section and the holes of the second plurality of holes can be elliptical in cross-section.
In preferred embodiments, the composite mold is dimensioned to be inserted into an apparatus for manufacturing oral brushes. In one embodiment, the mold further includes a plurality of cavities located at the first surface of the first component such that the pattern of holes extends from the cavities to the second surface, each cavity defining a portion of an oral brush from which tufts extend. In other embodiments, the mold further includes a plurality of the second components. In one embodiment, at least one of the holes of the pattern of holes is a bisected oval in cross-section.
In some embodiments, the second component includes a plastic selected from the group consisting of polyethylene, polypropylene, polyurethane, or a combination thereof. In other embodiments, the second component is metal.
In another aspect, the invention features a composite mold that includes: a) a bar having a plurality of openings extending therethrough, b) a first plastic component that includes a pattern of holes extending from a first surface of the first component to a second surface of the first component, the holes being configured to receive tufts that include at least one bristle, and c) a second plastic component that include a pattern of fingers that correspond to the pattern of holes, the fingers extending into the holes to form end walls, the first and second components being positioned in an opening of the bar. In one embodiment, the mold further includes a plurality of the first and the second components, each of the first and second components being positioned in an opening of the bar.
In other aspects, the invention features a method for forming a brush that includes contacting a first end of a tuft of bristles extending from a hole in an above-described composite mold with molding compound to form a brush.
In one embodiment, the method further includes inserting a second end of a tuft that includes at least one bristles into a hole of the composite mold such that the first end of the tuft of bristles extends beyond the composite mold.
In one aspect, the invention features a composite brush mold that includes a) a first component that includes a pattern of holes extending from a first surface of the first component to a second surface of the first component, in which the holes are configured to receive tufts that include at least one bristle, and b) a second component that includes a pattern of fingers that correspond to the pattern of holes, where the fingers extend into the holes to form end walls. Preferably the first and second components are plastic.
By using a composite mold, bristles may extend at a variety of angles to the surface of the brush head. The bristles can also extend to a variety of heights from the brush head. The ability to vary the topography of the second component while maintaining the same two-dimensional pattern at the base of the second component allows the use of multiple second components with a single first component.
Particular advantages exist when the first and second components are plastic. Plastic is inexpensive to manufacture and modify relative to the costs associated with manufacturing and modifying the topography in metallic molds, thus providing design flexibility. In addition, because the plastic component can be produced from a mold, the dimensions of the plastic component can be produced with excellent precision and accuracy. The plastic component also can be replaced when it wears out or is no longer working.
The properties of plastic enable the first and second components to maintain a sufficiently tight relationship with each other when the two components are mated to each other, while allowing the easy separation of the two components when disassembly is desired. The ability to disassemble the composite mold enables the mold and the holes therein to be easily cleaned.
In addition, because both the first component and the second component can be removed from the transfer bar, individual first and second components can be discarded and replaced without destroying the utility of the entire transfer bar. Once the defective component is replaced, the bar can be used at full capacity.
Other features of the invention will be apparent from the following description of the preferred embodiments thereof, and from the claims.